The past twenty years have witnessed an incredible variety of printers designed for digital computers. For years, the line printer was the mainstay of the computer industry. Then, in the mid-1970's, the personal computer revolution began with the appearance of primitive computers based on the S-100 bus. With the appearance of more user-friendly computers from Apple Computer and, later, from IBM Corporation, the demand for personal computers soared. The public's almost insatiable appetite for personal computers has spawned a virtual explosion of technology. Printer technology has been one of the principal beneficiaries of that technology explosion. Early on, dot-matrix printers grabbed the lion's share of the market. For less than a decade, daisywheel printers shared the limelight for letter-quality printing tasks. Thermal printers were briefly used for portable applications. High-resolution dot-matrix printers and ink-jet printers sounded the death knell for daisywheel printers. Though greatly reduced in number, dot matrix printers seem to have found a niche for multiple form printing applications.
Laser computer printers have been around almost since the beginning of the personal computer revolution. In late 1980, Xerox Corporation introduced a laser printer for mainframe computers. Retail priced at a lofty $298,000, it could print more than 30 pages a minute. However, it was not until the Hewlett Packard Company began marketing the LaserJet series of laser printers that laser printers for personal computers became commonplace. Color laser printers, which are now becoming more affordable, may eventually become as ubiquitous as the black-and-white laser printers.
Modern electronic printers (especially those employing laser copying technology) are often equipped with accessories such as optional media (e.g., paper) supply units, optional media output handlers such as sorters and collators, paper binding units such as staplers, and various other media handlers. These additional components generally require communications with the printer and some sort of power source. Typically, the power and communications requirements are handled with cables which interconnect the accessory to the printer. The use of cables is somewhat problematic for the following reasons:
(1) Power or communication disruption caused by wire breakage or inadequate securing of the cable ends; PA1 (2) Connector failure; PA1 (3) The added cost of providing a reliable cable and reliable associated connectors (two female and two male for each cable); PA1 (4) Inoperability of the equipment due to improper cable installation; PA1 (5) Damage occasioned by repeated connection and disconnection of the accessory over the life of the equipment; PA1 (6) Tangling of the cables; and PA1 (7) Procurement requirements.
Consequences related to the foregoing problems can be anything from merely an annoyance to printer inoperability. Inoperability is most likely to occur after an accessory has been removed or separated from the printer during media jam clearance and/or repositioning.
What is needed is a system for providing printer accessory power and communications without the use of cables or connectors.